Three dimensional printing is a generic term encompassing different additive manufacturing technologies such as inkjet printing, selective material deposition, material extrusion, material sintering and others. The object is produced by depositing a layer of a material on top or bottom of previously deposited or dispersed layer of material and because of this is termed additive manufacturing (AM) process. In a large majority of cases the material from which the object is produced is a polymer that adheres to the previously deposited layer and is hardened or solidified by actinic radiation, such as ultraviolet radiation, thermal sources and others.
Most objects are not simple in their structure and include segments of complex shapes such as curved surfaces and surfaces that could overhang outside the main body of the object or in case a hollow object, protrude into a hollow void or cavity inside the object defined by the object walls. The surfaces could be inclined, oriented at different angles and have different thicknesses or sizes. Different types of material layers having different properties and strength could be required to print such objects. Composite materials are among the strongest materials used in manufacture of different objects. Composite materials offer unusual selection of properties while additive manufacturing processes provide some advantages for fabrication of objects with complex shapes.
Some composite materials are manufactured by forming the object by deposition of a mix of components that include for example, fibers mixed with different resins. Mixes of metal and metal matrices, glass, ceramics and ceramic matrices elements with resins are also known. The carbon, glass or aramid reinforcements usually are supplied in the form of a fabric. The process is largely manual, although machines for laying down different material fabrics and spraying over them a resin exist. A sandwich structured composite is a special class of composite material that is fabricated by attaching two thin but stiff skins to a lightweight and thick core. The skins are the outer layers and are constructed out of a variety of materials. Wood, aluminium, and plastics are commonly used. More recently though, advanced fiber reinforced composites are being used as skin materials. The manufacture of such 3D panels is relatively a straightforward process, however manufacture of complex 3D shapes is more challenging.
Complex, three-dimensional shapes are used in building boats and ships where decks and hulls are commonly made with curved composite laminates or sandwich type structures. Ships utilize curved composite laminates and sandwich type materials to reduce ship weight. In aerospace, complex three-dimensional shapes have been used for wings, doors, control surfaces, tail planes, stabilizers for both military and civil aircrafts, vehicles, caravans, industrial machinery covers and other articles.
A plurality of complex objects or articles such as impellers, rotor and engine blades, and a variety of other objects could also be manufactured using 3D printing techniques. Generally, an infinite variety of articles and complex objects can be manufactured using 3D printing, Production of such complex objects requires production of special large size moulds that by itself is a complicate labour-intensive task.
Although the number of materials currently used in 3D objects manufacture is not large, it is suitable for manufacture of a large selection of 3D objects. The color of the available materials is somewhat limited and the size of the 3D objects produced by the existing equipment is also limited. Usually, large size products are manufactured in several pieces that must be assembled into a finished product, which could be a challenging task.
Printing of three-dimensional articles is described in several United States patents, including the following U.S. Pat. No. 5,204,055 to Sachs et al., U.S. Pat. No. 6,193,923 to Leyden, U.S. Pat. No. 6,397,992 to Sachs et al., U.S. Pat. No. 6,627,835 to Chung, U.S. Pat. No. 7,074,358 to Gybin, U.S. Pat. No. 8,309,229 to Nakahara, U.S. Pat. No. 8,974,213 to Yakubov, U.S. Pat. No. 9,162,391 to Yakubov, U.S. Pat. No. 9,216,543 to Lisitsin, U.S. Pat. No. 9,623,607 to Uzan, US Pat. Appl. Pub. No. 2003/0085383 to Burnell-Jones, US Pat. Appl. Pub. No. 20040198861 to Ohno, US Pat. Applic. Pub. No. 20070181519 to Khoshnevis, US Pat. Appl. Pub. No. 20110166056 to Huber, US Pat. Appl. Pub. No. 20150321385 to Stege.